The group was prepared for an overnight stay with tents, warm clothing, sleeping bags, food and water - but none had crampons or ice axes.
"If we had them it would have been a completely different story.
"I suppose the advice I would give anyone is you should seek local information about the place you're going to - we didn't do that."
Mr Chesneau contacted emergency services via his cellphone but lost reception soon after making the call and the group began preparing for what could have been a long night.
"It wasn't the fact that we were scared but we were in a really dangerous situation we needed to get out of."
Taupo senior constable Barry Shepherd said the incident was the latest in a series of near-misses at Tongariro National Park that had seen rescue services called out 25 times this year.
He said there was ample signage at the park warning of the dangers but many people ignored them. Many people were also not seeking local advice before setting out.
"There's definitely been an increase in these types of things this year and had these guys asked the locals 'would it be smart to go down Ngauruhoe today?' they [the local]) would have said 'you need some crampons'."
He said that there had been a trend of people finishing the crossing in pitch-black conditions and trampers without torches or head lamps were using the lights on their cellphones to help them see in the dark.
Taupo Youthtown Trust helicopter pilot Nat Every said there was a growing tendency among people to underestimate the Tongariro Crossing.
"It is the best part of a half marathon - if you walked that around town that would take four hours, but put a mountain in that as well and I think you have people underestimating what they actually have to do.
"People need to understand that even in summer the crossing can be bitterly, bitterly cold and they have to be prepared for all these scenarios - but they aren't."
Saturday's rescue follows another on April 28, when a party of 16 people ran into trouble, with some suffering mild hypothermia on the summit of the Tongariro Alpine Crossing.
The inexperienced group were lightly clad. Some were wearing shorts, others jeans and none had any alpine clothing, but were told by Tongariro Alpine Shuttles that the weather would improve.
New Zealand Mountain Safety Council avalanche and alpine programme manager Andrew Hobman said there were five "pretty straightforward points" on its website that people should consider before venturing out.
"We find that in most incidents in New Zealand it's usually one of these points that people hadn't adhered to that get them into trouble."
